The IEC 61850 Standard, Communications Networks and Systems in Substations, is an internationally recognized data communications suite of protocols for substation and system-wide protective relaying, integration, control, monitoring, metering, and testing. Currently IEC 61850 is the only substation protocol standard in substation automaton systems (SAS) that has high visibility in Smart Grid environments where, according to an IEEE survey, more than 200 countries have already accepted the standard. With multi-vendor installations, developers and users recognize the risk of varying interpretations of such a complex standard. Standard conformance testing and certification by test laboratories, carried out with standardized procedures and tools by experts who are not the designers of the equipment under test, can remove much of the risk and can bring a common understanding of how to implement communications so that all products work together.
It is understood, however, that device certification as compliant to the IEC 61850 standard does not guarantee 100% interoperable with other third-party devices, even though they themselves may also be certified as compliant. For example, interactions among otherwise compliant devices may be corrupted by design variables that are not specified or are only partly specified in the standard such as timing issues.
In theory, if the standard is clear in every detail and all the Intelligent Electronic Devices (IEDs) to be employed in a system have been conformance tested for all relevant services, then one would expect the IEDs to interoperate flawlessly.
If all the IEDs employed in a system are from the same development team, interoperation will likely be satisfactory. However, if the test combines IEDs from different manufacturers, or even different development locations of a single manufacturer, there is a chance that some standard specification interpretation differences will arise. This may be true especially if the relevant industry conformance testing program is in its early stages or if the standard is vague or silent on some necessary technical issues.
Most of the interoperability test procedures available today will connect two or more devices, for example, relays, and/or IEDs to a LAN and stimulate them to exchange IEC 61850 messages and exercise their interactive behavior. There are, however, no stringent methods presently available that can test interoperability under performance or loading conditions including client-server interoperability and common device configuration. In fact, interoperability testing is not within the scope of the IEC 61850 standard.
Devices that have passed conformance testing may still be subject to issues during integration, commissioning, and operation. Conformance testing is simply not equivalent to and should not be a replacement for interoperability testing.
US Patent Application Publication US20020173927 A1 to Vandiver discloses a “System For Testing Of Intelligent Electronic Devices With Digital Communications.” The test system provides conventional analog outputs that allowing application of power system conditions simulation to a device under test.
US Patent Application Publication US20090070051 A1 to Vetter et al. discloses an “Intelligent Electronic Device Configuration Verification” system that is described as a substation automation testing tool for IEC 61850 compliant substations.
In view of these known concerns there remains a need for accurate, reliable, flawless, automated and stringent interoperability test methods or procedures for the IEC 61850 standard.